Conveyer furnace



April 14, 1953 'D; P. COOPER CONVEYER FURNACE Filed Jan. 9, 1951 3 Sheets-Sheet 1 INVENTOR DAVID P. COOPER April 14, 1953' D. P. COOPER 2,634,964

ICONVEYER FURNACE Filed Jan' 9, 1951 3 Sheets-Sheet 2 INVENTOR DAVID P. COOPER yazmfll v D. P. COOPER CONVEYER FURNACE 5 Sheets-Sheet 3 Filed Jan 9 1951 R E P O O C P m m D Patented Apr. 14, 1 953 UNITED STATES PATENT OFFICE $634,964: CONVEYER FURNACE David P. Cooper, Youngstown', I1io,- assignor'to The- Gold Metal. Products. Company; Yams-- towm flhio; a corporation of:0hio:- Application January-9, 1951;,Serl'al'jNii; 205,187? 12.01am; (Crass-4n V 1 This invention relatest'o convey'er' furnaces'and more particularly to conveyer furnaces for heat treating: material passed through: the furnace while protecting the" material from oxidation: in I a protective atmosphere such as dissociated ammonia. I

In the accompanying drawings which illustrate several embodiments of my invention- Figure 1 is a: diagrammatic'si-de elevation of an annealing, furnace for annealing stainless steelstrip;

Figure-2 is a vertical section" through the heat--' in'g chamber' of the annealing furnace, taken on ticularlylto the annealing of stainless steelstrip'-,.

in arr'atmosphere of dissociated ammonia gas.

Referring-to Figures h3g an annealing furnace issh'ownin Figure-1' comprising a heating cham her 2" and a cooling chamber 3-. The heating chamber 2 isof themufile t'ype'havingacombustion chamber 4"and" amufiie chamber 5-; The

stainlesssteel strip- 6' fed froma pay-01f reel 1, passes over a guide-r0118; thenpassessuccessively through the mufile heatingchamber 5 and; thecooling chamber 3 on conveying rollers 9'; after which it passes over a guide roller Hl-an'ctis wound on'ajtake-up reel" H'. Dissociated ammonia-gas isfed'to the annealing furnace through a pipel-2--.-

The dissociated ammonia fillsthe'heating' chamberL'EI-andthe cooling chamber 3, thereby-protect ingjfthei steel strip from oxidation. A baffle l'-?F-islocated adjacent the entrance" and of the heating chamberi, a baffle'l'lliis located adjacent the exit adjacent the exit end of the cooling chamber 3.

The baffle l5. forms. a tight seal with the strip; whereas, the baflies l3 and I4 have substantially larger openings through which the strip passes. This arrangement insures that the bulk of the dissociated ammonia will} flow towards the strip entrance end; ofv the. furnace so as to sweep out any-contaminating gases or vapors that enter with the strip, which if permitted to be present end of the chamber 5 and a baffle l-5 is located at the time the-stainiess steel strip'ishot'enough; i

would oxidiie or stain the strip In order that the protective atmosphere of-dis-- soci'ated ammonia be efiective in protectingthe stainlesssteel' strip,- it is necessary that the conveying rollers S in the heating chamber and the I bearings" for such conveying roller be located entirely withi'rr the heating chamber; The usiial arrangement'for' conveyer furnaces is to htwe tlie' bearings for the 'rollerslocated on theoutside of l the heating" chamber; the 1 rollers: or stubscon-"- nected theretoextending through openingsinthe:

wall of the heating chamber. The openings are sealed toprevent loss of heat and protectiveat mosphere but such seals'are'not entirely satisfa'c tory whenannealingstainless steel in di'ssociated ammohiav 'I-headmission ot ev'erraslight amount Y of air into the heating chamber may resultin oxidizing of-flthe" stai'nless steel' being treated;

In accordance witumy invention, the-convey ing rollersand} the bearings for suoh=rol1ers are located entirely within -tlieheating chamber, the chamber not having any: openings: through which. the rollers or extensionsthereof proj ect'. the annealing of stainless =-steel stripin a dissociated ammoniaatmosphere, the strip is heated to a temperature the neighborhood of 2000? V F.

Alloysteel's grew andwarpund'er such conditions andare not entirely suitable as material for the I have found; however-,- that graphitebearings mayl be employed satisfactorilyunder suchconditions, One embodiment ofconveyingroller and graph- L itebearings therefor is illustrated in Figures 2':

bearings for the conveying rollers;

and 3a The conveying roller 9 shown in these"- fig-ures is= made of graphi-te; It.cou1d, however, bemadeof alloy steel or other suitablerefractory material? An alloy steel pin: l8: isfixed toieach-i end" ofthe-roller 9, as by. driving thetpinl with a. Each I pm has a portion I8a extending outwardly be.-

tight fit into Y a recess formed in therroller;

yond the end of theroller and" this portion; fits in a recess formed in a graphite bearing: l.9-., The bearing! I9: is; substantially barrele-shapedso that it can rock on its support 20. The: support 2 disiinthe form ot a saddlewhieh is-semircircular tocoriform to the contour ofthemufile chamber 5..

The support 20, is made of graphite; and is provided at its ends with: flanges. 21- which retain, the bearing 1 Sin place on its support.

The conveying rollers 9; are notfdri-venbut-turn merely dueto theaction oi the strip 6; supported thereby. In the embodiment shown in Figuresz,

and 3-,the pins [8. arev fiiiedtothe conveying roll ers and. rotate in the recesses, in the graphite bearings I 9 which'do not rotate.

Referring now to the embodiment shown in Figures 4 and 5, a series of alloy steel shafts 25 are spaced longitudinally of the annealing furnace and extend across the muffle chamber 5. Each shaft 25 is supported at its ends in a U- shaped bracket or support 26 which is secured to the interior of the mufiie chamber by welding 21. A graphite conveyer roller 28 is rotatably mounted on the shaft 25. The conveyer roller is provided with a pocket 29 at each end in which is located a substantially barrel-shaped graphite bearing 30, the bearings 30 being rockable in the pockets to compensate for misalignment due to warpage' or growth of the shaft. Each of the bearings 36 has a central bore 30a for receiving the shaft 25. In this embodiment the roller 28 and the bearings 30 rotate relative to the shaft 25 which remains stationary. The graphite roller'28 is provided with a hole 3| located centrally of the roller and connecting the two recessed 29. The shaft 25 extends through this hole. The roller 28 is provided at its mid-portion with a collar 32 which forms a bearing on the shaft 25.

Referring to the embodiment shown in Figure 6, a plurality of graphite conveyer rollers 35 extend transversely of the heating chamber 5. Each of the conveyer rollers has a deep pocket 35 formed in each of its ends, these pockets being connected by a smaller diameter bore 31. A plurality of barrel-shaped graphite bearings 38 are received in each of the pockets 3%, the bearings having slight spaces between'them to enable them to rock slightly. An alloy steel shaft 39 extends through the bores 40 of the graphite bearings and through the bore 31 of the conveyer roller. The ends of the shaft are supported in supports H secured to the inside of the heating chamber 5.

The arrangement shown in Figure 6- is similar to that shown in Figure 4 except that a plurality of graphite bearings are employed in each of the pockets 36 instead of a single bearing. In the arrangement shown in Figure 6 the shaft is supported throughout practically its entire length by the bearings, although each bearing is free to move independently of the other and is selfaligning. With this construction it is much more difiicult for the shaft to get out of alignment, but if it does get slightly out of alignment the bearings can still to a certain extent compensate for such misalignment.

In each of the embodiments shown for purposes of illustration, the conveyer rollers such as the rollers 9, 28 and 35 are made of graphite These rollers could, however, be made of alloy steel or other heat-resisting material, but in any case, in

accordance with my invention the bearings such as the bearings 19, 30 or 38 are made of graphite. j

Graphite bearings have been found to satisfactorily withstand the high temperatures when protected by extremely dry dissociated ammonia atmospheres.

The invention is not limited to the preferred embodiment but may be otherwise embodied alloy steel pin fixed in each end of the rollers and extending therefrom, graphite bearings inside the chamber for rotatably supporting said pins, and means connected to a source of dissociated ammonia for introducing dissociated ammonia into said chamber for protecting the graphite bearings.

3. A conveyer furnace comprising a heating chamber, conveying rollers in said chamber, an alloy steel pin fixed in each end of the rollers and extending therefrom, graphite bearings inside the chamber for rotatably supporting said pins, supports for said bearings, said bearings being rockable on their supports, and means connected to a source of dissociated ammonia for introducing dissociated ammonia into said chamber for protecting the graphite bearings.

4. A conveyer furnace comprising a heating chamber, conveying rollers in said chamber, an alloy steel pin fixed in each end of the rollers and extending therefrom, substantially barrel-shaped graphite bearings inside the chamber for rotatably supporting said pins, supports for said bearings, said bearings, being rockable on their supports, and means connected to a source of dissociated ammonia for introducing dissociated ammonia into said chamber for protecting the graphite bearings.

5. A conveyor furnace comprising a heating chamber, graphite conveying rollers in said chamber, an alloy steel pin fixed in each end of the rollers and extending therefrom, graphite bearings inside the chamber for rotatably supporting said pins, and means connected to a source of dissociated ammonia for introducin dissociated ammonia into said chamber for protecting the graphite bearings and conveying rollers.

6. A conveying furnace comprising a heating chamber, shafts extending across the chamber and mounted in supports located in the chamber, a conveying roller rotatably mounted on each shaft, graphite bearings interposed between the shaft and conveying roller, and means connected to a source of dissociated ammonia for introducing dissociated ammonia into said chamber for protecting the graphite bearings.

'7. A conveying furnace comprising a heating chamber, shafts extending across the chamber and mounted in supports located in the chamber, a graphite conveying roller rotatably mounted on each shaft, graphite bearings interposed between the shaft and conveying roller, and means connected to a source of dissociated ammonia for introducing dissociated ammonia into said chamher for protecting the graphite bearings and conveying rollers.

V 8. A conveying furnace comprising a heating chamber, shafts extending across the chamber and mounted in supports located in the chamber, a conveying roller rotatably mounted on each shaft, the conveying roller having a pocket formed in each end and at least one graphite bearing in each pocket for rotatable engagement with the shaft, and means connected to a source of dissociated ammonia for introducing dissociated ammonia into said chamber for protecting the graphite bearings.

9. A conveying furnace comprising a heating chamber, shafts extending across the chamber and mounted in supports located in the chamber, a conveying roller rotatably mounted on each shaft, the conveying roller having a pocket formed in each end, at least one graphite bearing in each pocket for rotatable engagement with the shaft, said graphite bearings being rockable in their pockets, and means connected to a source of dissociated ammonia for introducing dissociated ammonia into said chamber for protectin the graphite bearings.

10. A conveying furnace comprising a heating chamber, shafts extending across the chamber and mounted in supports located in the chamber, a graphite conveying roller rotatably mounted on each shaft, the conveying roller having a pocket formed in each end, at least one graphite bearing in each pocket for rotatable engagement with the shaft, said graphite bearings being rockable in their pockets, and means connected to a source of dissociated ammonia for introducing dissociated ammonia into said chamber for protecting the graphite bearings and conveying rollers.

11. A conveying furnace comprising a heating chamber, shafts extending across the chamber and mounted in supports located in the chamber, a conveying roller rotatably mounted-on each shaft; the conveying roller having a pocket formed in each end, at least one graphite bearing in each pocket for rotatable engagement with the shaft, said graphite bearings being substantially barrel-shaped and rockable in their pockets. and means connected to a source of dissociated ammonia for introducing dissociated ammonia into said chamber for protecting the graphite bearings.

12. A conveying furnace comprising a heating chamber, shafts extending across the chamber and mounted in supports located in the chamber. a graphite conveying roller rotatably mounted on each shaft, the conveying roller having a pocket formed in each end, at least one graphite bearing in each pocket for rotatable engagement with the shaft, said graphite bearings being substantially barrel-shaped and rockable in their pockets, and means connected to a source of dissociated ammonia for introducing dissociated ammonia into said chamber for protecting the graphite bearings and conveying rollers.

DAVID P. COOPER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,086,787 Whiteley July 13, 1937 2,308,609 Koch Jan. 19, 1943 2,332,232 Kauffman, 2d Oct. 19, 1943 2,368,886 Schroeter Feb. 6, 1945 2,549,666 Cope et a1 Apr. 17, 1951 

1. A CONVEYER FURNACE COMPRISING A HEATING CHAMBER HAVING CONVEYER ROLLERS AND BEARINGS LOCATED ENTIRELY WITHIN THE CHAMBER FOR ROTATABLY SUPPORTING SAID CONVEYER ROLLERS, SAID BEARINGS BEING MADE OF GRAPHITE, AND MEANS CONNECTED TO A SOURCE OF DISSOCIATED AMMONIA FOR INTRODUCING DISSOCIATED AMMONIA INTO SAID CHAMBER FOR PROTECTING THE GRAPHITE BEARINGS. 